public macro scope, and visibility

Jerry Messina · Post by **Jerry Messina** » Wed Oct 06, 2010 3:04 pm

I'm a little unclear on the scoping and usage of macros.

If I have a macro declared as public in file1.bas (ie 'public macro mymac()'), if I include file1.bas in other files should I be able to reference the macro with the same syntax used for other public entities (ie 'file1.mymac')?

To make it clearer, I have a module with a macro in it:

mymacro.bas

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module mymac

public macro mymacro(param1, param2)
    param1 = param2
end macro

end module

I'm trying to reference that macro in three other files:

mod1.bas

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module mod1

// has macro definition
include "mymacro.bas"

dim a, b as byte

public sub initialize()

    b = 0
    
    mymac.mymacro(a, b)
    
end sub

end module

and

mod2.bas

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module mod2

// has macro definition
include "mymacro.bas"

dim a, b as byte

public sub initialize()

    b = 0
    
    mymac.mymacro(a, b)
    
end sub

end module

and my main routine:

main.bas

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program test

device = 18F4685
clock = 40

include "mymacro.bas"

include "mod1.bas"
include "mod2.bas"

dim a, b as byte

b = 0

mod1.initialize()
mod2.initialize()

mymac.mymacro(a, b)

It doesn't seem to like the references to 'mymacro' in mod1 and mod2 no matter what syntax I try. However, it seems ok with the reference in main, using either 'mymac.mymacro(a, b)' or just 'mymacro(a, b)'.

It seems happy if I get rid of the mymacro.bas file and just place a private local copy of the macro in each of the files, but I was trying to get away from that.

Am I using it incorrectly?

David Barker · Post by **David Barker** » Wed Oct 06, 2010 3:18 pm

Jerry

Given that you have a BETA version of the compiler, I've updated your status to BETA tester so that you can post in the BETA section of the forum.

David Barker · Post by **David Barker** » Wed Oct 06, 2010 3:19 pm

I should add that I'll take a look at the above ASAP...

bitfogav · Post by **bitfogav** » Sat Dec 17, 2011 1:59 pm

Im also a little unclear on the scoping and usage of macros with the SF Compiler, would someone mind explaning how/why we would use a macro with the SF Compiler?

Jerry Messina · Post by **Jerry Messina** » Mon Dec 19, 2011 6:42 pm

David has fixed most of the issues I ran across, so macros pretty much follow the same sort of Public and Private
rules that apply to subroutines and functions.

Macros work much like declaring a subroutine 'inline' would. The code is placed inline where you invoke the macro,
so you don't have the overhead of the call/return. They work a bit different, though, when it comes to parameters,
and that's where they shine. The macro code is evaluated at the point where it's used, and any unused/redundant
statements are removed.

For example, consider some macros that I use to access the timer registers when using them in 16-bit mode, where you
have to read and write the registers in a particular order:

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// write 16-bit timer specified by 'tmr' with the value 'wval'
public macro write_tmr16(tmr, wval)
    if (tmr = 0) then
        TMR0H = (wval >> 8)
        TMR0L = byte(wval)
    elseif (tmr = 1) then
        TMR1H = (wval >> 8)
        TMR1L = byte(wval)
    elseif (tmr = 3) then
        TMR3H = (wval >> 8)
        TMR3L = byte(wval)
    else
        checkparam(etError, "unsupported TMR select")
    endif
end macro

// reads 16-bit timer specified by 'tmr', stores it in 'wresult'
public macro read_tmr16(tmr, wresult)
    if (tmr = 0) then
        wresult.byte0 = TMR0L
        wresult.byte1 = TMR0H
    elseif (tmr = 1) then
        wresult.byte0 = TMR1L
        wresult.byte1 = TMR1H
    elseif (tmr = 3) then
        wresult.byte0 = TMR3L
        wresult.byte1 = TMR3H
    else
        checkparam(etError, "unsupported TMR select")
    endif
end macro

If you were to say 'write_tmr16(1, $55AA)', that would end up translating to the following code:

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	TMR1H = $55
	TMR1L = $AA

All of the code for the 'if/elseif' tests disappear. You could also use the macro with a word variable instead of a constant value.

The 'read_tmr16' macro works much the same way

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	dim w as word
	read_tmr16(3, w)
	
	// would translate to
	w.byte0 = TMR3L
	w.byte1 = TMR3H

I use them mostly for routines that access hardware functions since they're quick.

bitfogav · Post by **bitfogav** » Mon Dec 19, 2011 9:44 pm

Thanks for explaining all that Jerry, makes more sense now